Inhibiting discoloration of vinylidene chloride polymers

ABSTRACT

A COMPOSITION CONSISTING ESSENTIALLY OF A POLYMERIZATE OF A MONOMERIC MATERIAL CONTAINING AT LEAST ABOUT 50 PERCENT BY WEIGHT OF VINYLIDENE CHLORIDE IN COMBINATION WITH COLOR STABILIZING AMOUNTS OF HYDROXYLAMINE HYDROCHLORIDE.

United States Patent O 3,817,895 INHIBITING DISCOLORATION OF VINYLIDENECHLORIDE POLYIVIERS Carl Moore, Midland, Mich., assignor to The DowChemical Company, Midland, Mich.

No Drawing. Continuation of abandoned application Ser. No. 177,129,Sept. 1, 1971. This application Apr. 6, 1973, Ser. No. 348,776

Int. Cl. C08f 1/88, 27/02 US. Cl. 260-2945 MN 2 Claims ABSTRACT OF THEDISCLOSURE A composition consisting essentially of a polymerizate of amonomeric material containing at least about 50 percent by weight ofvinylidene chloride in combination with color stabilizing amounts ofhydroxylamine hydrochloride.

This is a continuation of application Ser. No. 177,129, filed Sept. 1,1971, now abandoned.

BACKGROUND OF THE INVENTION It is known that dehydrohalogenation ofvinylidene chloride polymers, e.g., during fabrication at elevatedtemperatures, produces discoloration. It has further been found thatlatexes of vinylidene chloride polymers exhibit discoloration duringstorage, particularly when such latexes are alkaline in nature, i.e.,having a pH of between about 8 to 10. The color change is also believedto be the result of dehydrohalogenation of the polymer at the surface ofthe latex particles, accompanied by other chemical changes that generatechromophoric groups. This phenomenon occurs more rapidly as the surfacearea of the polymer exposed to the aqueous phase increases, i.e., as thesize of the polymerizate particle becomes smaller.

It is the primary purpose of the present invention to inhibit suchdiscoloration.

SUMMARY The above and related objects are attained by means of acomposition in accordance with the present invention which consistsessentially of 1) the polymerizate of a monomeric material containing atleast about 50 percent by weight vinylidene chloride with the remainderbeing at least one other monoethylenically unsaturated comonomer that iscopolymerizable with vinylidene chloride and (2) from about 0.05 to 4percent based on the weight of the polymerizate of hydroxylaminehydrochloride.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 3,817,895 Patented June 18,1974 The amount of hydroxylamine hydrochloride which is to be used willvary somewhat with the specific polymeric material and the use thereof,e.g., when used to stabilize latex materials the particle size of thepolymerizate is a significant factor in determining the amountsrequired, with smaller particle size polymerizates generally requiringlarger amounts of the stabilizing agent. Generally, the protectiveeffects may be noticed when as little as about 0.05 percent by weight ofstabilizing agent is used with at least about 0.2 percent based on theweight of vinylidene chloride polymer being preferred. The upper limitof stabilizing agent will be determined principally by economicconsiderations, however, in most instances there will be littleadditional benefit to justify the use of more than about 4 percent ofthe stabilizing agent based 0 the weight of the vinylidene chloridepolymer.

The stabilizing agent may be used in combination with 'vinylidenechloride resins which are to be thermally fabricated into shapedarticles as Well as in the preparation of polymeric latexes or lacquercoatings based on the vinylidene chloride polymers. When used tostabilize vinylidene chloride resins which are to be subsequently heatfabricated, the stabilizing agent may be physically blended with suchpolymer by conventional materials, or may be present during thepolymerization of the monomeric materials forming such polymers.

The stabilizing agent may also be easily incorporated into a polymerlatex by simple intermixing using conventional techniques. The latexcompositions may contain the usual additives, such as emulsifiers, dyes,pigments, light stabilizer and fillers that, pursuant to conventionalpractice, are suitable for incorporation in the polymer formulation.

The advantages of the compositions of this invention will be apparentfrom the following examples, wherein all parts and percentages are to betaken by weight.

Example I In each of a series of experiments, varying amounts ofhydroxylamine hydrochloride were admixed with a series of polymericlatexes. The following Table I sets forth the composition and propertiesof each such latex.

The following Table H sets forth the amount of hydroxylaminehydrochloride used and the effect on latex color following aging of eachlatex for varying periods of time.

TABLE II Percent hydrox Latex ylamine Latex color aiter aging (hours)desighydro- Latex Exp. No. nation chloride pH 1 16 24 70 Series I:

1 (1) None 9 P-W....:..- Sand.... Brown Brown...':.; Dark brown; (1) 0.59 P-W. P-W Tan Tan Dark tan; (1) 0.5 2 P-W. P-W.. P-W.- P-W. P-W.

(2) None 9 P-W Sand Brown Brown Dark brown; (2) 0.5 9 P-W P-W.- Tan TanDark tan.- (2) 1.0 9.1 P-W P-W Light tan... Light tan-.- Light tan; 20.5 2 P-W P-W.. P-W P-W P-W.

(3) None 9 Pink Yellow Brown Brown llgark rown; (3) 0.5 9 -.-do Pink TanDark tan-.. Dark tan. (3) 1.0 9 -.--do do Light tan--. Tan Tan. (3) 1 1.0 (1 ..d0.. -do Light tan--- Light tan. (3) 0.5 2 -d0 --d0 Pink PinkPink.

(4) None (4) 0.5 (4) 0.5

(5) None (5) 0.5 (5) 0.5

1 Latex pH adjusted by addition of NH4OH.

I Also contains 0.33% of the monosodium salt of N,N-dihydroxyethylglyeine.

A sample of latex (3) described in Table I of Example I was frozenovernight at F. and then thawed. The latex solids and serum were treatedwith ammonium hydroxide to elevate the pH with and without the presenceof hydroxylamine hydrochloride. After 24 to 48 hours aging, the solidsthat had been reslurried in deionized water and brought to a pH of 9.5with ammonia (in the absence of hydroxylamine) were brown in color. Byway of comparison, equivalent samples (but containing 1 percent byweight of hydroxylamine hydrochloride) were a light sand color afteraging and were unchanged in color from that observed in the originalrecovered solids. The serum in all samples did not develop any colorupon agmg.

1. A process of inhibiting dehydrohalogenation induced discoloration ofpolymeric latexes said latexes having a pH of between about 8 and 10 andwherein the polymerizate present in said latexes is composed of at leastabout 50 percent by weight vinylidene chloride with the remainder beingat least one other monoethylenically unsaturated comonomer comprisingthe post-addition to said latexes of from about 0.05 to 4 percent basedon the weight of said polymerizate of hydroxylamine hydrochloride.

2. The process of claim 1 wherein said monoethylenically unsaturatedmonomer is selected from the group consisting of acrylonitrile, theacrylate and methacrylate esters, vinyl chloride, vinyl acetate, vinylpropionate, vinyl benzoate, isobutylene, 2-sulfoethyl methacrylate,acrylic acid, methacrylic acid, itaconic acid, maleic or fumaric acidsor half esters and aconitic acid. 7

References Cited UNITED STATES PATENTS 3,075,937 1/1963' Bilow 260-29.6MN 3,597,381 8/1971 Ripley 26029.6 MN 3,644,317 2/1972 Monaco et al.260-29.6 MN 3,706,705 12/1972 Koyanagi et a1. 26029.6 MN

LUCILLE M. PHYNES, Primary Examiner US. Cl. X.R.

